Oscar fredrik svante carlson



UNITED STATES PATENT OFFICE.

CIGAR FREDBIK SVANTE CARLSON, OF LJ'UNGAVERK, SWEDEN, ASSIG-NOR TO AKTIEBOLAGET NITROGENIUM, OF STOCKHOLM, SWEDEN.

METHOD OF MANUFACTURING NITROGEN COMPOUNDS FROM CARBIDS.

1,33 7,750. No Drawing.

To all whom it may concern.-

Be it lmown that I, Oscar: FREDRIK SVANTE CARLSOX, a subject of the. King of Sweden, and resident of Ljungaverlqin the Kingdom of Sweden, have invented certain new and useful Improvements in Methods of Manufacturin Nitrogen Compounds from Carbids, of w ich the following is a specification.

It is Well known that nitrogen compounds are manufactured from' carbide by causing nitrogen to act upon the carbid at an increased temperature. The most important one of such nitrogen compounds is the so called lime-nitrogen (calcium cyanamid) which is produced by causing nitrogen to act at an increased temperature upon calcium carbid or a mixture of the substances from which it is produced, viz. caustic lime and carbon,

The manufacturin of calcium cyanamid is still unsatisfactory 1n spite of essential im'- provements which have been made. For instance, the result of manufacturing on a technical scale is essentially inferior to what it should be according to the theory. The main reason for this may be due to the fact that the temperature increases so rapidly, at least at certain points in the exothermic reaction, that the calcium cyanamid formed by the reaction, will dissociate or melt, whereby the nitrogen is prevented from penetrating completely into the mass of carbid.

In order to increase the yield and to accelerate the reaction, it has been proposed to supply the nitrogen at a relatively high pressure, at which pressure the result will be still more improved, if indifferent sub-' stances are added to the mixture of the substances in question, which indifferent substances are also heated during the reaction and thus act in an endothermic manner on account of which the temperature can be kept within such limits as to prevent said inconveniences.

Howevera method of working at which the gas pplied at a high pressure will cause man considerable inconveniences in practice. he furnaces should have a very strong construction in order to stand the high pressure owing to 'which fact they will be very expensive. Further, it is impossible to avoid great losses of nitrogen in furnaces of the size necessary for industrial working, which will make the pro .s uneco- Specificatlon of Letters Patent.

Patented Apr. 20, 1920.

Application filed July 29, 191a Serial No. 112,067.

nonlical. Finally, in using a hi h pressure of the gas, the danger of an explosion must always be taken into consideration.

The present invention relates to a process of manufacturiup nitro en compounds from carbide in vertical she} -furnaces or in furnaccs of some other construction, which process consists in keeping the mass stirred by means of special rake-hke stirring implements in order to facilitate the penetrating of the gas into the said mass. In this method the said disposition of the mass to melt on account of too high an increase of temperature has caused very great diflicnlties as the mass has stuck :to the stirring implements, owing to which fact irregularities of working have arisen. V The present :invention thus relates to a process by the use of which said difficulties will be removed to the greatest extent. The lnvention is based on the observation that if the mass of carbid is stirred during the progress of the reaction or during a conslderable part of it either continuously or intermittently and if the stirring is forced to a certain intensity, the reaction between the nitrogen and the mass of car-bid can be accelerated to such a degree that the yield will be particularly large with a very inconsiderable loss of nitro en and without irregularities of working lithe carbid is mixed with indifferent substances in such a degree that the temperature of the carbid furnace is prevented from rising to the temperature at which the cyanamid will dissociate or the mass will melt. For the same purpose an addition of catalytic substances ma be used, for instance fiuorid of calcium eit er alone or mixed with the indifferent substances.

The quantities of indifierent and catalytic substances may be varied within rather wide limits. When the percentage of added inigredients is increased, the mixin may be ess intensive, and'when it is re need, the

mixing may he more intensive, the intensity 100 of the mixing being intimately connected with the percentage of catalytic and indifferent substances and the temperature in the different parts of the furnace. If the mixing is not intensive enough with respect 105 to the quantity of additions, the mass will sinter to a block, and the temperature will at the same time rise too much, whereby the mass sticks fast to the stirring implements,

the lime-nitrogen formed is dissociated, and 110 economical conditions of manufacture are disturbed. This proportion is easily and simply settled in an experimental way for each type of furnace.

As an example it may be stated that ii said substances are added in such a quantity as to make the charge contain 3:3. of the same. and the reaction is performed at atmospheric pressure or, as often used in prac tice. at a pressure a little above atmosphcz i for instance. a tow nun, ol the column of mercury. it will be possible to obtain a crude calcium cyanamid ha ing a proportion of nitrogen up to 203. lloweven quite good results may also be. obtained by a lower proportion of inditl'erent substances. lor instance 10";

In this process the loss of nit rogcu is particularly small, and in industrial worle in; theloss ol' nitrogen is only about 2W The improved yield of calcium e'anamid from the process 'above described is accord ing to the inventor due to the fact that the. added indil'l'erent substances being also heated, absorb a great part ol' the heat. at reaction disengaged and thereby prevent too great an increase of tenqierature. lt' simultaneously a catalytic substance is present this will cause a setting'in and continuing of the reaction to a complete reaction at a lower temperature than usual. A melting of the mass is thus avoided, which fact on one hand makes the complete and uniform penetrating, of the gas into it possible and on the other hand. prevents the mass from sticking to the stirring implements, on account of which irregularities of working are avoided.

The above high utilization of the nitrogen may be due to the fact that the stirring in the presence of indilferent and catalytic substances causes a very uniform distribution of heat and thus uniform absorption throughout all the mass.

Further the fact should be noted as a new and surprising result of this new process that instead of obtaining a cyanan'lid of compact stony quality there is obtained a porous coke-like product without any disseminated clods of carbid which have not been subjected to the reaction. The cyanamid of this quality can be more easily crushed than the product obtained by the methods heretofore known.

Hy using a high pressure above atmospheric simultaneously with stirring and the above additions, a result still more favorable as to the yield may be obtained.

'hat I claim is:

'lhe herein described method of manufacturing nitrogen compounds in a vertical shelf furnace from carbid and nitrogen, consisting in heating the cal-bid intimately mixed with inditl'erent and catalytic substances in the fnrnacein presence of nitrogen and stirring the carbld mixtureonits way through the furnace on each shelf to regulate the temperature and fluidity 0f the mass, the intensity of such stirring bein determined by theamonnt of indifferent and catalytic substances added.

In witness whereof I have hereunto signed my name.

OSCAR FREDRIK SVAN'IE GARLSON. 

